The proposed project is a systematic biochemical investigation of the structure and function of animal cell surfaces. Particular attention is focused on the glycoprotein components and their role in cancer and developmental biology. Structural studies on the surfaces of L cells are designed to answer such questions as: How many distinct glycoproteins are found on the surface of the L cell and how many copies of each are present? How are the carbohydrate portions arranged on protein and can one protein "carrier" contain more than one type of carbohydrate? Are cell surface glycoproteins metabolically stable and at what time during the cell cycle are they synthesized? Complementary studies are intended to clarify the function of individual cell surface glycoproteins. Accordingly, experiments are designed to exploit situations where one expects differences in cell surface glycoproteins to accompany differences in cell function. Two such instances have been selected for particular attention. They are: (1) Contact inhibition of growth in 3T3 mouse fibroblast cells. Biochemical differences in the cell surfaces of contact inhibited and virus-transformed, non-contact inhibited 3T3 cells will be characterized in detail. (2) Cellular differentiation in neuroblastoma and myoblast cells. Glycopeptides characteristic of the differentiated state of both of these cell types will be identified and related to their biological role.